docs: def _get_site_response_term(self, C, imt, vs30, sa1180):
          """
          Compute and return site response model term see page 1033
          """
          # vs30 star
          vs30_star = self._get_vs30star(vs30, imt)
          # compute the site term
          site_resp_term = np.zeros_like(vs30)
          gt_vlin = vs30 >= C['vlin']
          lw_vlin = vs30 < C['vlin']
          # compute site response term for sites with vs30 greater than vlin
          vs30_rat = vs30_star / C['vlin']
          site_resp_term[gt_vlin] = ((C['a10'] + C['b'] * self.CONSTS['n']) *
                                     np.log(vs30_rat[gt_vlin]))
          # compute site response term for sites with vs30 lower than vlin
          site_resp_term[lw_vlin] = (C['a10'] * np.log(vs30_rat[lw_vlin]) -
                                     C['b'] * np.log(sa1180[lw_vlin] + C['c']) +
                                     C['b'] * np.log(sa1180[lw_vlin] + C['c'] *
                                                     vs30_rat[lw_vlin] **
                                                     self.CONSTS['n']))
          return site_resp_term